Excitatory synapse

Definition

An excitatory synapse is a type of synapse where the binding of neurotransmitters leads to an increase in the likelihood of an action potential occurring in the postsynaptic neuron. This process typically involves the opening of sodium channels, allowing positive ions to flow into the neuron, resulting in depolarization. Excitatory synapses play a crucial role in facilitating communication between neurons and are essential for processes like learning and memory.

5 Must Know Facts For Your Next Test

1. Excitatory synapses primarily use neurotransmitters such as glutamate, which is the most abundant excitatory neurotransmitter in the brain.
2. When an excitatory synapse is activated, it results in depolarization of the postsynaptic neuron, moving its membrane potential closer to the threshold needed to trigger an action potential.
3. The effectiveness of excitatory synapses can be influenced by various factors, including receptor density and the availability of neurotransmitters.
4. Long-term potentiation (LTP) is a process associated with excitatory synapses that strengthens synaptic connections and is believed to underlie learning and memory.
5. Dysfunction of excitatory synapses has been implicated in several neurological disorders, including epilepsy and schizophrenia.

Review Questions

• How do excitatory synapses facilitate neuronal communication and what role do they play in action potential generation?
  • Excitatory synapses facilitate neuronal communication by releasing neurotransmitters like glutamate that bind to receptors on the postsynaptic neuron. This binding typically opens sodium channels, allowing positive ions to flow into the neuron and leading to depolarization. If this depolarization reaches a certain threshold, an action potential is generated, allowing signals to be transmitted along the neuron. This process is vital for efficient information processing in the nervous system.
• Compare and contrast excitatory synapses with inhibitory synapses in terms of their functions and mechanisms.
  • Excitatory synapses increase the likelihood of an action potential in the postsynaptic neuron through depolarization, typically mediated by neurotransmitters like glutamate. In contrast, inhibitory synapses decrease this likelihood through hyperpolarization, often using neurotransmitters such as gamma-aminobutyric acid (GABA). While excitatory synapses facilitate signal propagation and enhance neural circuits, inhibitory synapses play a crucial role in balancing neural activity and preventing excessive excitation, thus maintaining homeostasis within neural networks.
• Evaluate the implications of excitatory synapse dysfunction on neurological health and how this can influence cognitive functions.
  • Dysfunction of excitatory synapses can lead to significant neurological health issues, as these connections are critical for proper communication between neurons. Conditions such as epilepsy arise when there is excessive excitation due to overactive excitatory synapses, leading to seizures. Furthermore, impairments in excitatory transmission have been linked to cognitive deficits observed in disorders like schizophrenia and autism. Understanding these implications highlights the importance of excitatory synapses in maintaining both neural health and cognitive functions.

Related terms

neurotransmitter: Chemical messengers released from a neuron that transmit signals across a synapse to another neuron or target cell.

action potential:

A rapid rise and fall in voltage across a cellular membrane, which occurs when a neuron is activated and sends signals down its axon.

inhibitory synapse:

A type of synapse where the binding of neurotransmitters decreases the likelihood of an action potential occurring in the postsynaptic neuron.